1. Field of the Invention
The present invention relates to transducer arrays. More particularly, the present invention relates to transducer arrays having substantially direction-independent responses.
2. Description of the Related Art
Linear electroacoustic arrays are of interest for both consumer and professional audio applications for several reasons. In many scenarios, for instance in enhancing hands-free speech reception in an adverse environment, the inherent directivity of the array is the key advantage. In other cases, the directivity is indeed problematic, for instance in the use of a loudspeaker array for wide-area listening. For the application of audio reproduction, there is a benefit in using an array of drivers in that an array can achieve a higher-level acoustic output than any one of the individual constituent drivers. Rather than using a single larger driver to achieve a desired output level, a multiplicity of smaller drivers can be deployed; this array approach enables loudspeaker form factors that are commercially practical and attractive from an industrial design perspective. However, there is a drawback in such applications in that the frequency response of an array is angle-dependent such that the listening experience is significantly degraded at off-broadside positions unless the array is specifically configured to reduce such degradations.
A number of approaches have been proposed in the literature to counteract the variability of an array's response. These include filter network frequency invariant beamforming and Bessel weighting. Unfortunately, many of these approaches sacrifice gain in order to provide a relatively invariant response. What is desired is an array design that provides improved gain while limiting the variation in the response.